Some Renesas SoC based boards mux SD and eMMC on a single sdio
controller, exposing user control by dip switch and software control by
gpio.

Purpose is to simplify development and provisioning by selecting boot
media at power-on, and again before starting linux.

Add binding and driver support for linking a (gpio) mux to renesas sdio
controller.

Signed-off-by: Josua Mayer <josua@solid-run.com>
---
Changes in v2:
- dropped mux-controller node from dt binding example
  (Reported-by: Conor Dooley <conor@kernel.org>
   Reported-by: Krzysztof Kozlowski <krzk@kernel.org>)
- Link to v1: https://lore.kernel.org/r/20251128-rz-sdio-mux-v1-0-1ede318d160f@solid-run.com

---
Josua Mayer (2):
      dt-bindings: mmc: renesas,sdhi: Add mux-states property
      mmc: host: renesas_sdhi_core: support configuring an optional sdio mux

 .../devicetree/bindings/mmc/renesas,sdhi.yaml      |  6 +++++
 drivers/mmc/host/Kconfig                           |  1 +
 drivers/mmc/host/renesas_sdhi.h                    |  1 +
 drivers/mmc/host/renesas_sdhi_core.c               | 27 +++++++++++++++++++---
 4 files changed, 32 insertions(+), 3 deletions(-)
---
base-commit: 3a8660878839faadb4f1a6dd72c3179c1df56787
change-id: 20251128-rz-sdio-mux-acc5137f1618

Best regards,
-- 
Josua Mayer <josua@solid-run.com>